Parents and students from ground zero exchanged horror stories of surviving the World Trade Center disaster during their return to makeshift classes in other schools yesterday.

“It was the worst day of my life,” said 9-year old Griffin Van Lent, a student at PS 234 in TriBeCa, who was reassigned to PS 41 in Greenwich Village.

Griffin’s father, Nicholas, an architect, whose office is near PS 234, picked up his son after the first plane crash. They then saw the second plane ram into the south tower from Dad’s 16th-floor office.

Nicholas asked Griffin if he saw the debris falling from the buildings.

“No, Daddy,” Griffin replied. “Those are people.”

Willa Barth said her fifth-grade son, Asa, has been traumatized by the tragedy. She said he’s been thinking about the horrible ways of dying.

“Asa saw the entire disaster happen,” Barth said. “He’s not sleeping well. He’s not eating well. The best thing for him is to be with other kids.”

Beth Rubin, who lives on Warren Street, within blocks of the obliterated Twin Towers, said she and her two children were taken out of the area by pedicab bicycle.

“We thought the towers would topple on the school,” she said.

Some students from the HS for Leadership in Public Service said they’re thankful to be alive. The school is at 100 Trinity Place, in the heart of ground zero, and the kids were relocated yesterday to the Fashion Industries HS on West 24th Street.

“Everyone in the school thought we were going to die. We thought all the buildings were going to crash,” said Samantha Defeo, a 14-year-old freshman.

Rafael Noorani’s mother, Angela, is still upset.

“Part of me is happy Rafael is back to a normal routine. Part of me is still afraid. I’m afraid of the effect on the kids,” Angela Noorani said. “We teach kids not to join gangs and not do violence. And then we see this happen.”